Monthly Archives: December 2010

Snow-covered UK seen from space

In January I posted an image from NASA’s MODIS satellite showing the UK covered in snow. I’m doing the same for the recent snow; these images were taken today (1st December) between 1110 and 1430.

The problem with this image is that snow and clouds are both white so it’s difficult to tell the difference between the two. Luckily NASA also provides some false colour imagery at long wavelengths (670 nanometres, 876nm and 2155nm) that makes this job easier.

Ice is very absorbent in the 2155nm band (shortwave infrared) that is assigned to the red channel of the image, but reflects in the visible red (670nm) and near infrared (876nm) bands that are assigned to the green and blue channels respectively, causing ice to appear cyan. Vegetation is absorbent in both the near and shortwave infrared which leaves it looking green.

Higher resolution imagery is available from the NASA MODIS Rapid Response System.